1. Field of Invention
The disclosed device relates to a scleral implant. More particularly it relates to a device which is implanted in the sclera of the eye for the treatment of excess intraocular pressure which frequently accompanies Glaucoma and for the treatment of presbyopia or loss of accommodation of the eye.
Glaucoma is an eye disease wherein the patient gradually loses sight. Such vision loss is caused by damage to the optic nerve which acts like an electric cable and communicates images from the eye to the brain. High intraocular pressure frequently accompanies Glaucoma and is one of the main causes of the nerve damage causing this vision loss. It is thought that increased intraocular pressure is caused when the eye's drainage canals become clogged over time. The intraocular pressure rises to levels causing damage because the correct amount of fluid can't drain out of the eye in the normal fashion. If this excess intraocular pressure is not detected and treated, it can cause a gradual loss of vision. Such a vision loss in some cases occurs over a long period of time. However, in some cases of glaucoma the eye pressure usually rises very fast. It is thought that this happens when the eye drainage canals are blocked or covered over, like the clog in a sink when something is covering the drain.
Drugs are frequently used on cases where intraocular pressure slowly builds and frequently work well. In patients suffering a rapid rise in such pressure or a long term rise that has reached a dangerous plateau, severe eye damage and permanent loss of sight can result.
Surgery has also been used more recently to treat intraocular pressure. Clinical investigators have noted in recent years that intraocular pressure is lowered following radial incisions in the anterior sclera, known as an anterior ciliary sclerotomy. Unfortunately, for patients undergoing such a procedure, the beneficial effects are negated over a period of time following the procedure as the incisions heal and scar. Consequently the potential for eyesight loss arises as pressure again builds following the surgery.
Another sight related problem affecting patients is that of Presbyopia which is a vision condition in which the crystalline lens of a patient's eye loses its flexibility. flexibility makes it difficult for a person to focus on close objects. While Presbyopia may seem to occur suddenly once the patient discovers the problem, it is generally accepted that the cause of the sight loss is actual loss of flexibility of the lens which takes place over a number of years and usually becomes noticeable in the early to mid-forties.
Treatment to help you compensate for presbyopia includes prescription reading glasses, bifocals, contact lenses, and laser surgery. However such corrective lenses can be inconvenient to the wearer and laser surgery to the cornea of the eye carries with it the inherent risk to the eyesight itself if a mistake is made.
Still further, many diseases that attack the eye and eyesight require the long term administration of drugs to maintain eyesight. It is desirable to provide an easily placed device that would provide long term modulated direct communication of drugs into the eye concurrently with helping correct the internal pressure and possible vision problems of the patient.
Consequently, there is a continuing need for a medical treatment that would a require simple surgical procedure that would have long-lasting effects to relieve internal eye pressure and for the correction of presbyopia to eliminate or reduce the need for prescription lenses and without risky surgery on the lens of the eye itself. Such a treatment would be further enhanced by the provision of a drug delivery system that can be modulated for dose and time that would aid in internal pressure relief as well as other eye ailments requiring precision or long term delivery of drugs.
2. Prior Art
Surgical procedures and implantable devices have recently been developed to address the presbyopia.
U.S. Pat. No. 6,280,468 (Schachar) discloses a scleral prosthesis for treatment of presbyopia and other eye disorders. Schachar teaches the placement of a prostheses in a plurality of pockets slightly smaller than the implant, circumferentially around the pupil, to exert an outward pressure on the sclera thereby restoring the working distance of the ciliary muscle allowing the patient relief from presbyopia. However, Schachar is oriented circumferentially around the pupil or front of the eye and lacks an anchoring means to hold the implants in proper position in the sclera over the long term which can result in shifting of the implant reducing or eliminating its effectiveness. Further, the use of tunnels smaller than the implant tends to cause broken implants. Schachar also lacks a drug delivery means from the implant. Still further, actual dismounting of the implant can occur which would require removal from the eye especially if it pierces the outside surface of the eye when shifting in position. Additionally, the circumferential placement of the implants is not as effective at encouraging internal drainage and reduction of intraocular pressure.
U.S. Pat. No. 6,102,045 (Nordquist) discloses a method and apparatus for lowering intraocular pressure of the eye. However Nordquist is a filtering implant which extends into the anterior chamber of the eye through an opening in the limbus cornea. Nordquist lacks the ability to correct presbyopia that a sclera-mounted device provides and because of its delicate positioning and communication directly with the anterior chamber Nordquist is harder to position correctly. It also lacks the ability to infuse drugs to the eye and the provision of direct communication between the anterior chamber and the exterior regions of the eye increases the risk of infection to the anterior chamber.
U.S. Pat. No. 6,079,417 (Fugo) discloses a method and device for reshaping the cornea to change its topography. However Fugo lacks the ability to increase the drainage from the eye interior to lower intraocular pressure. Fugo also is designed to mount directly into the cornea layer of the eye.
U.S. Pat. No. 5,178,604 (Baerveldt) teach the use of an implant for increasing eye drainage and reduce pressure caused by glaucoma. However Baerveldt is simply a tube which communicates directly with the interior chamber of the eye and offers no aid to rectifying presbyopia.
As such, there is a continuing need for a reliable operative method and prostheses that will aid physicians in interrupting the relentless cycle that results in vision loss and eye damage to patients suffering from building intraocular pressure in the eye. Such a device should be insertable into the eye in a relatively easy procedure for a trained surgeon. Such a device and procedure should avoid the more delicate structures of the eye and should also avoid communicating internal eye structures directly with the exterior of the eye to prevent infection. Such a device would provide additional utility by through the optional ability to provide a drug delivery system from the implant directly to the eye. Still further, the device implanted by this method should be dimensioned with an anchor structure to insure that the implant stays properly positioned in perpetuity thereby alleviating the need for replacement or removal caused by dislocatable implants and maintaining a fixed correction of vision.